\documentclass{article}
\usepackage{booktabs}

\begin{document}

\begin{tabular}{|p{120pt}|p{240pt}|}
\toprule
Mode & Description\\
\midrule
Vertical mode & Building the main vertical list, from which the pages of
out put are derived.\\
\hline
Internal vertical mode & Building a vertical list for a vbox\\
\hline
Horizontal mode & Building a horizontal list for a paragraph\\
\hline
Restricted horizontal mode & Building a horizontal list for an hbox\\
\hline
Math mode & Building a mathematical formula to be placed in a horizontal list\\
\hline
Display math mode & Building a mathematical formula to be placed on a line by
itself, temporarily interrupting the current paragraph\\
\bottomrule
\end{tabular}

\end{document}
